### May 12,2016 Federal Aviation Administration New England Region Engine and PropellerDirectorate Engine Certification Office (ANE-142) 1200 District A venue Burlington, MA 01803 Attention: ANE-142 (Chris Spinney)

# 0~!!!~~, 400 Main Street, East Hartford, Connecticut06108



### Subject: AMOC to AD 

### 2013-02-02: Removal ofCFM56-3 Series Engine HPT Disks Manufactured by Pratt & 

### Whitney (STC SE00034EN) Reference: 1) P&W Special Instruction 6F-12, "Field Management Plan for OMS HPT Disks with Possible Low Creep Properties", dated December 21, 2012

Mr. Spinney; 2) DRAFT: P&W Special Instruction 6F-12 Revision A, 

### "Field Management Plan for OMS HPT Disks with Possible Low Creep Properties", dated May 17, 2016.
Attached please find a copy ofAD 2013-02-02 and the referenced P&W Special Instructions. The subject Airworthiness Directive requires removal from service offive high pressure turbine (HPT) 

### disks manufactured by Pratt & 

### Whitney at reduced life limits due to a forging process error. These disks are included in P&W Supplemental Type Certificate SN00034EN for incorporation in CFM International CFM56-3 series engines. In paragraph (c) ofthe AD, and in the P&W Special Instruction (reference 1), the five serial numbers of the disk are in error. Two letters were transposed. The Table below shows the serial numbers as written in the AD and Special Instruction, and the correct serial numbers. Incorrect Serial Numbers As Shown in AD and Sl Correct Serial Numbers GLKBAA9307 GKLBAA9307 GLKBAA9335 GKLBAA9335 GLKBAA9404 GKLBAA9404 GLKBAA9407 GKLBAA9407 GLKBAA9409 GKLBAA9409

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### As a result ofthis error, Pratt and Whitney requests an Alternate Means ofCompliance to allow the use ofrevised Special Instruction, 

### 6F-12 Revision 

### A, dated 

### May 17, 2016 which has the correct 

### serial numbers. No other change was made to the Special Instruction. Please contact this office ifthere are 

### any questions. Sincerely,



# ~lr??r~ Certification & 

### Airworthiness FAA-Designated Engineering Representative Attachments cc: 

### Glorianne Niebuhr

Subjectto the export control and proprietary restrictions on the first page ofthis doc:umenlSPECIAL INSTRUCTION NO. 6F-12 REVISION A May 17, 2016 

### Field Management Plan for GMS HPT Disks with Possible Low Creep Properties APPLICATION: This Special Instruction (SI) is for GMS High Pressure Turbine (HPT) disks P/N 880026 installed in CFM56TM engine serial numbers E721528-02, E724785-02, E721613-02, E721878-02 and E721121-02. THE REASON FOR SPECIAL INSTRUCTION: SUMMARY: DUE TO A MANUFACTURING MATERIAL PROCESSING ISSUE. FIVE P/N 880026 HPT ROTOR DISKS SHALL HAVE THEIR LCF MAXIMUM LIFE LIMITS REDUCED. Problem: Five P/N 880026 HPT disks currently in service may not meet the published LCF Maximum Life Limit as indicated in the Time Limits section of the STC engine manual (Ref. 1). Cause: Due to a manufacturing material processing issue, the material properties ofthe disks may not be as expected and creep properties in the disk rim could be less than the design intent. A possible change in blade slot geometry may increase stress on the HPT blades at the disk/blade interface and cause the blades to have reduced LCF life. Solution: The LCF Maximum Life Limit for the five HPT disks shall be reduced. To determine the impact on the HPT blades, the HPT disk's blade attachment area shall be dimensionally inspected to determine if there has been a change in geometry due to creep. See Accomplishment Instructions for specific field management information. APPROVAL: The Field Management Plan as described in the Accomplishment Instructions of this Sl is FAA approved. WARNING
-- This document contains technical data the export of which is or may be restricted by the Export Administration Act and the Export Administration Regulations (EAR), 15 C.F.R. parts 730-774. Diversion contrary to U.S. law is prohibited. The export, re-export, transfer or re-transfer of this technical data to any other company, entity, person, or destination, or for any use or purpose other than that for which the technical data was originally provided by P&W, is prohibited without prior written approval from P&W and authorization under applicable export control laws.

Distribution Code Special Distribution Internal Reference No. JRM 121C008A 

### Page 1 of 4 This export marking supersedes all existing export notes in this document. This document has not been Export classified. Do not Export.

### SPECIAL INSTRUCTION NO. 6F-12A

DESCRIPTION: For five HPT Disk P/N 880026, serial numbers GKLBAA9407, GKLBAA9409, GKLBAA9404, GKLBAA9307 and GKLBAA9335, remove from service and return to Pratt & Whitney for dimensional inspection as indicated in the Accomplishment Instructions. REFERENCES: (1) GMS CFM56-3TM STC Engine Manual P/N PW9325M80-1, 05-00-00 "EngineAirworthiness Limitations - Time Limits" (2) P&W Supplemental Type Certificate No. SE00034EN NECESSARY TOOLS: No more Support Equipment is necessary. ADDED DATA: A. Mixed Thrust Management: When determining total cycles remaining on each disk that is used in multiple model or thrust installations, it is permissible to use the following formula: 

# r PTC (Type . U. ) J 1- PTC (Type B) 8000 - PTC (Type C) } x LLC (fo r Type) = LRC (forType) 

# l 8000 4000 Where: PTC =Part Total Cycles Accrued for each Type LLC =New Maximum Life Limit Cycles LLC (Type A)= 8000 LLC (Type B)= 8000 LLC (Type C) = 4000 Type A= CFM56-3B-1 or CFM56-3B-2 or CFM56-3C-l operating to 20.1K lbs MTO Type B = CFM56-3B-2 or CFM56-3C-1 operatingto 22.1K lbs MTO Type C = CFM56-3C-l operating to 23.5 K MTO LRC= Life Remaining Cycles



### Page 2 of 4

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### SPECIAL INSTRUCTION NO. 6F-12A

ACCOMPLISHMENT INSTRUCTIONS: 1. HPT Disk P/N 880026, S/Ns GKLBAA9407, GKLBAA9409, GKLBAA9404, GKLBAA9307 and GKLBAA9335 installed in engines indicated in Table 1 should be removed from service and deemed unserviceable the next time the parts are available at the piece part level, or at a time not to exceed the New Maximum Life Limit indicated in Table 2 below, whichever occurs first. Table 1 Engine Serial Number HPT Disk P/N 800026 Serial Number E721528-02 GKLBAA9407 E724785-02 GKLBAA9409 E721613-02 GKLBAA9404 E721878-02 GKLBAA9307 E721121-02 GKLBAA9335

### Table 2 Model and Thrust Rating Maximum Life Limit New Maximum per Ref. 1 Life Limit CFM56-3B-1, CFM56-3B-2 or CFM56- 20,000 cycles 8000 cycles 3C-1 operating to 20.1 K lbs MTO CFM56-3B-2 or CFM56-3C-1 18,500 cycles 8000 cycles operating to 22.1 K lbs MTO CFM56-3C-1 operating to 23.5K lbs MTO 16,600 cycles 4000 cycles Note: While the HPT disks ofTable 1 are in service, it is permissible to use Mixed Thrust Management to determine remaining cycles using the formula in Added Data.
2. Return disks to Pratt 

### &Whitney. Contact Manager, Customer Technical Service, for instructions for return of parts.



### Page 3 of4

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### SPECIAL INSTRUCTION NO. 6F-12A

3. The HPT blades removed from each disk shall not be eligible for overhaul processing until it is confirmed that the HPT disk meets blade slot dimensional requirements. a. When removed from the engine, the HPT blade serial numbers and the associated HPT Disk serial number should be documented and the blades held pending dimensional inspection of the HPT disk
. b. The HPT disk should be returned to Pratt & Whitney for dimensional inspection ofthe blade slots to confirm that creep has not occurred
. Acceptable blade slot geometry is all blade slots conforming to blueprint dimensional requirements , except normal wear from blade contact is permitted. c. When it is confirmed that HPT disk blade slot geometry is dimensionally acceptable, held HPT blades may be released for overhaul processing. If it is determined that blade slot geometry is not acceptable , the HPT turbine blades shall be deemed unserviceable and not eligible for overhaul processing and scrapped
.
MATERIAL INFORMATION: A. No new material is being provided by this Special Instruction B. See Table 1 for affected engines and parts.



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